1. Field of the Invention
The invention relates to a method and apparatus for high performance switching in a network system such as token ring, ATM, ethernet, fast ethernet, gigabit ethernet environments, LANs, WANs and other known data communication routing network systems. In particular, the invention relates to a system and method for prioritizing packet flows within a network.
2. Description of the Related Art
The Internet Protocol (IP) is the underlying protocol for routing packets over the Internet and other TCP/IP-based networks. Recent innovations in the IP has transcended the Internet into a global network that provides a universal method of packaging information for delivery across an endless variety of network systems and transmission media. In fact, the ease and popularity of communicating via the Internet has placed greater demands on the IP to transmit a variety of data at an extremely high transmission rate. Many applications that currently run on the IP can function with whatever bandwidth they obtain from the network because they have elastic bandwidth requirements. In the Internet community, such applications are typically supported by best-effort services. The global IP is a best-effort service because it delivers packets of information across the network with no guarantee that those packets will arrive on time, arrive in a particular order, or arrive at all. In addition, communications over the IP may be made through a connectionless or a stateless service. A connectionless service exists when no prior agreement is made between the sender and the receiver to watch over or manage the delivery of a packet. A stateless connection occurs when the sender does not retain any information about the client that might be used to maintain a connection or to assist in the next requests. No information is cached in expectation of the user's next request. In contrast to a stateless connection, a stateful connection is a connection in which some information about a connection between two systems is retained to maintain the current connection or to use for future connections.
Unfortunately, such connectionless and stateless connections may cause transmission problems for some of the new breed of Internet applications, such as multimedia, which require significant bandwidth for transmission. Other applications, such as IP telephony and other real-time or two-way transmissions, may also suffer from a connectionless or stateless connection because these applications also have very strict transmission timing requirements. These time-sensitive applications typically require the rapid transmission of voice or video packets over the network during a real-time or two-way communication between two or more network users. For instance, IP telephony relates to the products, standards, and techniques for carrying voice calls over the Internet.
To mitigate the transmission problems associated with voice and video packets, some network designers have suggested increasing the bandwidth. However, increasing the bandwidth alone is not a sufficient solution to address the current demands on the IP. Therefore, what is needed is a novel method of providing a level of assurance to the network that its Quality of Service (QoS) can be satisfied. A QoS guarantee warrants the timely delivery of information on networks, control bandwidth, set priorities for selected traffic, and provide a good level of security. QoS is usually associated with being able to deliver time-sensitive information such as live video and voice while still maintaining enough bandwidth to deliver other traffic, albeit at a lower transmission rate. Managing the QoS within a network usually requires prioritization of the packets, which relates to scheduling the traffic of some packets so that the packet maneuvers through congested networks before the traffic flow of lower-priority packets.